Advise to turn a thin router guide bush adapter

I want to turn a thin router guide bush adapter from a square aluminium piece. I planned the sequence in the image attached. I’m worried about facing the square in step 7 when holding the part on only 2.5mm of material. Any advise will be appreciated.

Ivan

Ivan

Several ways to machine this part, my method as follows.

1. Mount in 4j and face.
2. Turn C 40mm diam 3mm depth.
3. Bore B 30mm diam thro all.
4. Remove from 4j and fit in 3j on 40mm diam C  
5. Face to to leave 3mm thickness.
6. Turn A 60mm diam.
7. Bore D 34.1mm 2.5mm depth.

Emgee

Edited By Emgee on 30/07/2021 23:07:27

Holding on 2.5mm with soft jaws would be fine.

Jim

Another vote for soft jaws, will happily hold down to 1mm thickness, just don't take silly depths of cut. You also get an edge to push the work back against so it won't wobble.

+1 for soft jaws, but if you don't have that as an option then make a single use split collet. Turn a suitable piece of material Ø60 x 10 and bore Ø40. Put a step on one side so that you have a spigot Ø50 x 5. Not all that different from your part. Turn it around with the spigot in the chuck jaws (Tap it down onto the jaws and mark where jaw one is for repositioning in the same place each time) face off just enough to give a true face. Take it out and saw cut through to the bore and deburr. You can now mount your part in this split collet and put it in the chuck and tap it down in the same place as before. It will grip the part without marking and support the part you want to face off.

Martin C

Thank you all for the advice,

I followed Emgee’s sequence as I don’t have soft jaws and was not concerned about marking on the part. I however ended up making a 50mm split collet to hold the part in the 3 jaw as my chucks front most outside jaws could not close to 40mm. It worked great.

Ivan

Ivan

Making a split collet is always worthwhile if you want concentricity better than the chuck provides also gives a complete grip on the diameter, far better than in the 3 jaws only.
Another of Joe Pi's excellent tips.

Pleased it worked out OK for you.

Emgee